Pencil sheath composition



Patented Nov. 28, 1933 2 v I I NI ED; STATES-Q P ENT armrams-sumsCOMPOSITION I Jorgen Thomsen,'Jersey- "City, N'. J.,"assignor' to JosephDixon' Crucible Company, T'Jersey' Qity, J., a corporation of New Jersey8 I No Drawing. Application Dece niber 12, 1931 r Serial No. 580,139

The invention relates to an improvement in: flour; a bondingagent suchas casein-or viscose, plastic compositions forpencilsheaths'and simiasolvent and plasticizing agent for the casein;v lar articles. Thisapplication is a continuation if; the latteris used,andusually'a'coloring-mattenii in part of my copending application,Serial No.1 Ihave discovered that one of thereasonswhy 492,370 filedOctober 30, 1930. comp0siti0n}.pencil sheaths aspheretofore com- 55 Ithas been proposed heretoforetossubstitute" pounded become warped ortwisted is the fact for the usual wood sheath for' lead and other thatsome of the ingredients :used have required pencils a sheath composed.of a self-hardening too much waterto makethe compositionextrusn plasticcompound. Up to the present-time, how-' ble. This fact led-me tosearchfor equivalent 10 ever, so far as I am aware, no practicalcomingredients whichare non-absorbent, or substane 60 pound, has beendisclosed, because the 'requiretially so, and which can be eitherusedwithor. ments .of' the art are so-varied'and confiicting substitutedfor the former watereabsorbing inl- I For example,the sheathproducedmust'beinitialgredients. For example, arpencil sheath*com-% v 1y soconstituted thatit can be extruded from a position composed largely offinely powdered: celsuitable machine whileit is in a plastic,condilulose, such as wood-flour, is highly 'water ab- 65 tion; it mustbe capable of surrounding, and upon sorptive, whereas the-fibrouscoating of certain drying, of contracting and firmly'gripping thecereals, such as rice and maize products, and lead or other markingmaterial;- itv must be 2 fibers, such as. those obtained from cocoanutcapable, of being easily'and smoothly 'cut by a hulls, cornstalks,sugarcane stalks and the like,

knife oripencil sharpener; it should have a subare. substantiallynon-absorbent. By suitably 70 stantially'smo'oth exterior for'theapplication of comminuting the rice hulls and/or the other a coating orfinishing material such as' j'apan or substantiallynon-,absorbent'fibers and mixing varnish, should one be required; and ingeneral, them .in various proportions with the cellulose; the pencil?sheath composed of the plasticcom flour, there can be produced anon-warpingan'd I pound must resemble the natural .wood sheathnon-twisting pencil sheath. I have alsodi scov 75 in all its qualitiesas nearly as possible. Not only ered that this new mixture of powderedceumose' I I must the composition sheath meet thespractiand finelycomminuted non absorbent fibrous cal requirements, it must'alsomeetth'e'c'oinm'ermaterial can be bondedin an improved manner I cialrequirement of being manufactured" at a by' the' use of a stablewater-solublev compound,

price permitting it to'compete with wood sheaths. such .as casein, orpreferably, a mixture of casein 30 'One reason why the plasticcompositions hereand .a v s table-water-soluble cellulose compound,tofore proposed for pencil sheaths have not'met such as an alkylderivativeof cellulose These all the requirements is that they haveshrunk alkyl cellulose, compounds are at the presentv or contracted toomuch on drying and the pencil time, available in the open market'andarewa-tersheaths composed of them have warped andsoluble bindingagents.advantageouslyused in twisted. The principal objectofthe-presentincomposition. 'Ihey,may be prepared, for invention is to produce acomposition pencilsheath stance, inthe manner described ,in1the patentswhich will not only meet the practical'requireto Lilienfeld Nos;1,188,376 and;1,505,043 and merits set forth above but will also havethe addinurnerousothers. -However, it is more convenient p 40 tionaladvantage that the pencil composedLof topurchase the alkyljcellulose;binding agent I the new compound will remain straight and notfromamanufacturerthereof.1 Althoughan alkyl warp or twist. cellulose isthe preferred bonding agent, its-mar- The improved composition forpencil sheaths ket price sometimes prevents its use, in which casecontains several ingredients which have not hereit may be partly orwholly replaced by casein; 45v tofore been proposed for this purpose andwhich, Viscose has been proposed as a bonding agent combined with theusual pencil sheath composi for pencil sheath compositions, but I prefernot tion ingredients, produce the improved pencil to use'viscose becauseit'is' not stable. It begins sheath. Pencil sheath compositions ingeneral to harden irreversiblyat 70 F., and slowly decontain a fiber orfibrous material, such as ascomposes even at low temperatures, so thatun- 50 bestos, a fine cellulose material such as wood usual precautionsmust be taken in preparing it as a bonding agent, and it eventuallyloses its bonding characteristics in the composition.

By way of example of the preferred embodiment of my invention, I givethe following specific formula Percentage Ingredient (by Weight) Alkylcellulose binder n 2 Casein 17 Lime 2 Sodium fluoride 2. 5 Turkey redoil 4 Wood flour 54 Comminuted rice hulls 18.3 Coloring matter 2 Thepreferred composition for pencil sheaths given above may be compoundedin the follow ing manner:-The alkyl cellulose is dissolvedin fourv timesits weight of boiling. water, and the casein is mixed with about 125parts of cool water.

To themixture of alkyl belluloseand casein is added the lime-mixed withabout parts of water, and then the sodium fluoride mixed with about 50"parts of water --is added. The whole mixture is thoroughly stirreduntil the mass is in plastic condition. The turkey redoil and the color'are'next thoroughly stirred into the mass,

Tandthen a mixture of the wood fiour and the comminuted rice hullsis-added and the mass stirred until the composition is homogeneous. Inthis condition the plastic composition can be the purpose of pencils. ar 7 -If the price of alkyl cellulose is too high for use in making thepreferred form of pencil sheath, an excellentsubstitutepencil'sheath,"very slightly producing composition sheath Theforegoing composition can be compounded in .substantially the samemanner described for the preferred composition;

Casein is a granular powder, it is therefore necessary to plasticize'itso as to convert it into a bonding material. it with a basic hydroxide,such as lime or amifi-monia, orwith a salt, such as sodium fluoride orsodium phosphate. If it is desired to substitute; ammonia for the sodiumfluoride or sodium phos phate, then it is'desirable to add apreservative and'strengthening agent, such as hexamethylenet tetramineor phtalic anhydride. From one tovtwo I per cent of these preservativeand strengthening extruded from the machines usually employed for I Thiscan be done by mixing agents is sufficient. The turkey red oil acts as asoftening agent for the casein. Soap or rubber substitute, that is,sulphonated oil, may advantageously be substituted for the turkey redoil; I

The proportions of 'thewood flour or other powdered cellulose and thecomminuted rice hulls or other fibrous material may vary considerably.

Y I have found, however, that a non-warping and non-twisting compositionpencil sheath can hardly be produced if a less proportionthan ten rialis used in the composition. And on the other hand, if too great aproportion of rice hulls or similar fibrous material is used, then thecomposition pencil sheath loses in appearance and is also likely-to be-tougher and not so easily cut by-the knife or-the pencil sharpeningmachine.

Accordingly, I have found that it is not desirable to use more thantwenty or twenty-five per cent of rice hulls or equivalent fibrousmaterial.

The addition of the coloring matter to the mixture is optional.

I WhatI claim is: I

1. A pencil sheath composition comprising a major quantity of woodflour, a minor quantity of a substantially non-water absorbent,comminuted cellulosic fibrous material, and" a Water-soluble binder- 2.A pencil sheath composition comprising a" major quantity of a. finelycomminuted woody per cent of rice hullsorequivalent fibrousmatematerialas its chief ingredient, a minor quantity i of finelycomminuted. substantially non-water absorbent cellulosicfibrous'material, and a watersoluble cellulose compound as a bindertherefor.

3., A pencil sheath composition comprising a major quantity ofwoodxfiour asitschief ingredient, about 10 to 25% of a substantially.nonwater absorbent, finely comminuted cellulose.

material, and a water-soluble binder.

4. A pencil'sheathrcomposition comprising a major quantity of woodflour, about 10 to 25 percent of comminuted ,rice hulls, "and a watersoluble cellulose compound-as a binder; V

5; A pencil sheath compositionrcomprising the following ingredients insubstantially the given percentages by. weight: alkyl cellulose bindingagent 2%, casein 17%, lime 2%, sodium'fiuoride 2.5%, turkey redi oil 4%,wood flour 54%;, comminuted rice hulls 18.3 and coloring matter .2

6. A pencil sheath composition-including. a.

major quantity of a finely comminutedcellulosic' material having markedwater absorbing properties and a minor quantity of a finely comminutedcellulosic material of greatly less waterv absorbing :propertiesjo,reduce the tendency of the pencil sheath to warp, twist and shrink. 1

7. A pencil sheath composition including a major quantity of a finelycomminuted cellulosic material having, marked water absorbing propertiesand a lesser quantity, amounting to about,

10 to 25% of the total solids,of a finely comminuted cellulosicmaterialof greatlylesswateri absorbing properties-to reduce the tendencyof the pencil sheath to warp, twist and shrink.

JORGEN E. THOMSEN.

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